Brake



April 17; 1945. E. A. MOLLENHAUER 7 2,374,117

' BRAKE Filed Feb. 23'. 1944 2 Sheets-Sheet 1 gwi'wwtom I imef fljlfollenimuen P 1945- 'a A. MOLLENHAUER' 2,374,117

BRAKE Fil ed Feb."23, 1944 2 sh ets-sheet 2 EifizerJZ/Voz iuzur Patented Apr. 17, 1945 1 BRAKE t.

' Elmer A. Mollenhauer, Spokane, Wash., assignor 7' of one-half to R. Guy

Wash. I

Buchanan, 59 K3 Application,February 23,1944, Serial No, 523,568

6 Claims; (o1.188 795) This invention relates to brakes and it is primarily an object of the invention to provide means to take up automatically excessive clearance between the drum and shoes such ,as comprised in the general type of hydraulically op-.

erated vehicle brakes.

A more particular object, of the invention is to provide means entirely within the wheel cylinder of a hydrauliobrake'system for automatically adjusting the brake shoes with respect to their associated drum and wherein suchmeans functions at all times without requiring manual adjustments. J--

The invention also hasvfor an object to provide a-slack adjuster for a'hydraulic brake system for placement within a. wheel cylinder of the system and in such position to operate in oil at all times and thus materially increase. the life of the adjuster. Y r

The invention also has. for an object to provide means for automatically maintaining the,v

brake shoes of a hydraulic brake system adjusted at all times at the proper clearances with respect to the brake drums and wherein such means includes a slack adjuster positioned as a separate unitwithin each of the wheel cylinders of the brake system and wherein each of said slack adjusters or units operates entirely separate and distinct from any of the other slack adjust ers or units within other of. the wheel cylinders of the system. v j

The invention consists in the details of cone struction and in the combination and arrangement of the several parts of my improved brake whereby certain important advantages are attained, as will behereinafter more fully set forth.

In order that my invention may be better understood, I will now proceed to describe the same with reference to the accompanying drawings, wherein:

Figure l is an elevationalview and of a somewhat diagrammatic character illustrating a slack adjuster constructed in accordance with an embodiment of the, invention and in applied position;

Figure 2 is an enlarged detail sectional view taken through the upper portion of Figure 1;. v

Figure 3 is a sectional view'taken substantially on the line 33 of FigureZ;

Figure ,4 is an enlargedfragmentary sectional view of the slack-adjuster as herein embodied, with the parts in initial position; 1

Figure 5 is a view similar to Figure 4 but showing certain of the parts in a second position;

Figured is also aview'similar to'FigureAbut. flange. 6. This outer end a and flange .6 are showing'certain of the parts in position; and e Figure 7 is .a detail sectional view taken substantially on the line 'l-I of Figure 6. 7

As illustrated in .thelaccompanying drawings,

D denotes a conventional brake drumwith which coact the well known type of articulated brake:

shoes. S carrying the usual type of brake linings L for direct contact with the drum D upon pansion of theshoes S. v

The opposed free ends of the shoes S are con tacted by the pressure caps P slidably mounted upon the opposite end portions of. the wheel cylinder C suitably supported in desired position between the opposed, free ends of the shoes S,

as by the backing plate or cover for thedrum D.

The linings L of the shoes S are normally held, from contact with the drum D by the brake shoe pull back or release spring B.

Working within the wheel cylinder 0, are the pistons I having their inneror opposed faces provided with the sealing cups 2. Fluid is admitted within the wheel cylinder C at a point intermediate the pistons I, or more particularly the cups'2, through an opening 3 which has-communication with a suitable. conduit leading from a master cylinder as is well known' in'connection with hydraulic brake systems now generally in use. Interposed between the pistons and more particularly the cups 2 thereof is an expansible spring 4 of requisite tension for holding the pistons l against displacement.

As the pistons I are forced outwardly under the influence of the fluid admitted within the cylinder through the opening 3, the pressure caps P will be correspondingly outwardly moved and by contact with the adjacent free extremities of the shoes S, bring the linings L into desired frictional contact. with the drum D. i

The foregoing structure is conventional and in is assured that the life of the adjuster unit A will v be materially prolonged. r

The adjuster or unit A, as herein embodied comprises an elongated cylindrical body 5 of required length and which hasits outer end a fiat and defined by the outstanding surrounding fiat a sun further adapted to have direct contact with one of the cups 2.

Closely but freely surrounding the body is an idler sleeve 1 of a length less than the length of the body 5 and closely but freely surrounding the applied idler sleeve 1 is an adjuster sleeve 8 of a length substantially equal to the length of the body 5. The outer end of the adjuster sleeve 8 is defined by an outstandifigzsurrounding fiat fiange 9 for contact with the cup 2 of the second piston l.

The flange 6 of the body 5 and the flange 9 of the adjuster sleeve 8 are maintained in contact with the cups 2 by the expansion spring l and cause the adjuster to follow autbmatically' outward movement of the pistons f and" cups 2i Anexpansible member I8 is interposed between the outer end of the idler slecveif andlatretaines washer ll properly fitted within the outer end of the adjuster sleeve 8. This washer lfp'rovides' means to facilitate the desired assembly crap-unit'- or slack adjuster.

The outer extremity ois the? idlersle'eve I is provided at desired pointsz spaced cirfcurnferential'ly thereasround: withthe outwardly and: radially directed: pins lzzrigid with: the: sleeve; 7. Thesez'pi'ns t2:work withinthe longitudinally dis-- posed: slots M provided". the outer end: portion ofitiho adjusteir sleeve 8; whereby: the: sleeve: a is allowed a limited extentlotcoutwardl' endwise movement independently oi thezidler sleeve" 1", the

=: extent or: such: outward independent movement:

being limited by' contact with the inner ends 11 ct tiiexslots: lit: with the: pins; 122: The: slots: Id

extendthrougnthe collar o and have theinouter ends open;

The body? at the end portion thereoffiimmedl ately adjac'entlto the flange 6 isprovided there-- along with the longitudinallyspaced and raidrlah 1y? disposed socketslE; the inner ends or which have:- in: communication: therewith thev restricted I openings IE in: which freely m'ovel the: outer end porti'onsofl the-elongated: adinsterpins H1.

The: inner end portionv ofi eachiof these pins:

I'I-'calrries a: head l 8'which closelyi'fits withina) socket t5; and withim the socket l 5 an'd bearing against thehead' l8 isian expansible member E9- of; requisite tensions herein disclosed as acoil spring; outerend ofthe socket k5,: as herein disclosed, is closed by a;- removableplug with which-the expansible member ls directly-engages; although thisari afigement may bevai ied asdesired;-

The; springs- I 9 constantly urge; outwardly the ins; |T "bl)l'-li inifih initial 'assembly or theunit ois adjhster these pins H are lield retracted within the body 5' by the 1 idler sleeve 1 which; the initial assembly, has its ill-nor endportionoven' lying the outer extremities-of all' of the pins: W: This initial; assembly ofntheiadjusteror 'unit is maintainedby a in M which is freely inserted through the sleeves l and 8 as afforded by the properly: positioned openingsn an'dmhioh'openings's 22in the initial'assemblywh therazdjuster or: unit are inzregisterazid ailsocin register: with: a rezressflziimthe: peripheryrofithezbody i inlwhicn: is received: the: inserted end portion: of; meiap pliedlholdingpirtz'lt 'Tlieouter -end; oi this aipplied pin: M has slil itably secured thereto a linki tag;- wire 2f?- tagtwira 24 is at a length to extend' out. through the air bleach openings fi andithrmigmwhtch tlne pirtl 2r wilt also: passa sd thatwireamfspiir be readily" withdrawnsaftezr the sla'cicad lusteror unit beert re laced. ltii mi cb vious that the tag wire 24 and pin 2! can be readily threaded from within through the usual l :idl'ersleeve 1 will'b'e' held against endwise displacement along. the body 5 by the spring H. However, as the inner ends b of the slots l4 contact with the l2, the continued relative outwardmovement between the body 5 and sleeve 8 will" result in the inner end of the sleeve 8 andthe adjacent irmeiirendofthesleeve 1 freeing; theiinnerniost-pin H" which will. then move outwardly'under action. ofaits spring: [9' to lock thebodyi'member b andthe 'sle'eve 8 againstrelative inwardi endwise movement; As the: linings L continue to move, this operation willcbe repeated, resultingtin; the: successive release o'it the pins l'l.

It isbelieved to bereadil'y/ apparent that by theuseoitthe slack'adju'ste'r as herein embodied.

the brake shoes-S;v or more particularly the liningstlithereof,wills-automatically be; keptat the proper clearancewith-irespect to the. brake drum D and as each brake cylinder has own slack adjuster, it will be: at; once apparent that: the

I brake system asarwhole the brake: shoes associated with: brake": drum,=- Will be automamically'adijusted to their proper: clearances in dependently ot theothers; This: is'of. advantage 4 because if one set of brake shoes many" one of the wheels sliculdwear more than: the: othergt'he slack adjuster crunit associated with such wheel will automaticallyadjust that set of shoes to the proper clearance without afiecting theother vl li'e'els- Aitenthe bra-keiihingsr of a set otibrak'e shoes" become wornrout, the :slack ad juster has' its parts so proportioned as toreach the endof its1adjustmg: ability therefore; will: become idle and not selfithe brake; shoes-put any farther.-- Thlsis of advantage asunder such-condition. the operator will know that the adjuster wzlo'es'rno't,seem to tak'aup-the -cl'earance between the-shoes andthe drumand that it is necessary to pump thebrake pedal to obtain brakagee This: will clearly givewarning that the. linings Li-are worn out and thatthebrakes s should be-r'e'lined;

idler" sleeve: I, however, operates'not only to allow normal travel ofthe device Without releasing the pins l I when the br ake' shoes S are adjusted to the proper clearance but this idler sleeve-1 isial'sol employed to offset any abnormal condition: (it the brake: drums which-may be:

cheat-ens. by: heat: after continued: brake applicationtcauses: the :d rum ntoz expand, thus ,necessi-= tating the brake shoes S to travel farther to moire:

requisite: c'ontactwlth the: D. If it' were not rfior: :thi'sa-idl'et" sleeve 'thoi'dingrtha pins: I]: in their oftposition: whilerthisiabnormat condition exists, normal functioning ofi the adjuster. device wouldi. occur: and it would be; of: disadvantage uponw coritractiomresultl-ngrirono cooling: or the drum. I

Theslots l-aeinrthersleaea aresc ealibrat'edas to allow: this; sleeve 8 to-travel i ts normal-dis taiice-plusthe extra distance'whichzmay bemused by the expanded drum before the inner ends of the slots l 4 contact the lugs [2 of the idler sleeve 1 to pull the idler sleeve 1 to uncover or release the pins H for the desired automatic adjustment.

It is believed to be readily apparent that if no allowance was made to compensate for the drum expansion caused by heat, there would be probability of the device being set up a notch while the drum is in this expanded condition and. upon cooling of the drum and its return to normal size, the brake shoes S would be too tight and thus cause the brake to drag or even lock. It is, therefore, an essential purpose of the sleeve 1 to control the adjusting device in a manner to prevent setting itself during this abnormal drum condition.

From the foregoing description it is thought to be obvious that a brake constructed in accordance with my invention is \particularly well adapted for use by reason of the convenience and facility with which it may be assembled and operated.

What is claimed is: g i

1. A slack adjuster for use in a hydraulic braking system including a wheel cylinder and'opposed pistons working in such cylinder and operatively connected with the brake shoes,

comprising a plurality of members assembled beone member for movement perpendicular to the line of movement of the members for progressively limiting relative inward movement of such members after said members have had predeter- -mined relative separatory outward movement. I

2. A slack adjuster for placement between the pistons working within a wheel cylinder of a hydraulic brake system to automatically take up the wear of the brake shoes, comprising two telescopic members, the outer ends of each having contact with the pistons, means for constantly urging said members 'in such contact and to effect relative outward movement of such members, and separate and independently acting elements carried by one of said members at spaced points longitudinally therealong for successive coaction with the second member to prevent relative inward movement of said members. v 3. A slack adjuster for placement within a wheel cylinder of a hydraulic brake system, comsleeve to have initial outward movement independently of the first sleeve, said means also operating to lock the two sleeves at such initial relative movement, and holding elements carried by the member at points spaced therealong, said elements being successively released upon relative outward movement of the sleeves andthe member to engage one of the sleeves to hold the sleeves and member against relative inward movement.

4. A slack adjuster as set forth in claim 3, wherein the elements each comprise a springpressed pin disposed radiallywithin the memher, said pins being initially held depressed by the first sleeve but progressively released upon relative outward movement of the sleeves and member.

5. 'In a hydraulic brake, including a piston cylinder and a pair of pistons disposed in the cylinder to be forced. apart by fluid introduced under pressure therebetween; a slack adjuster comprising two telescopically assembled members I interposed between the pistons, means normally urging outward separatory movement of" the members and maintaining an outer end of each member against a piston, aplurality of independently operating latching elements carried by one of the members and arranged to be successively-brought into operation upon relative separatory movement ofthe members, and means for restraining the actuation of the latching elements for a prescribed relative outward movement of the members.

6. A hydraulic brake slack adjuster as set forth in claim 5, in which said restraining means comprises a sleeve interposed between the telescopically joined members, means yieldingly maintaining said sleeve in a position to restrain said latching members, and means establishing an operative coupling between the sleeve and one of the telescopically joined members upon a pre- ELMER A. MOLLENHAUER. 

